Smelling coolant in the tailpipe...I think.

Dear Car Talk

Dear Car Talk | Aug 01, 1997

Dear Tom and Ray:

I have an '84 Ford Mustang with a V6 engine and 143,000 miles. My
problem is that a lot of steam comes out of the tailpipe. Then when I
step on the accelerator, water comes out of the tailpipe, and I think it
smells like antifreeze. Is this a problem? -- Jose

TOM: Not necessarily, Jose. Water and steam are perfectly normal. Water
is a by-product of the combustion process, and when it comes out of the
engine, it's hot, so it comes out as steam.

RAY: And if the tailpipe is cool, some of the steam condenses on its way
out and dribbles out as liquid water. So that's no problem.

TOM: Losing antifreeze out the tailpipe WOULD be a problem, though. But
since smells can be deceiving, you really have to use more than just
your nose to make that diagnosis. You have to turn instead to automotive
stoichiometry (that's scientific jargon for seeing if you have any less
coolant in the car than you had, say, yesterday).

RAY: If you are losing coolant, and it's not dripping from anyplace
obvious, then you may have a blown head gasket, cracked cylinder head or
cracked engine block -- which cost $400, $1,200 and $2,000 to fix,
respectively -- give or take a few hundred bucks.

TOM: But if you're not losing a lot of coolant, you have the option of
simply leaving it alone. On a car with 140,000-plus miles, that's
probably what I'd do. I'd keep an eye on the coolant level to make sure
it doesn't run low and melt the engine. Then I'd just keep driving and
start saving for the inevitable repair -- or down payment on a '97.

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